1. Field of the Invention
The present invention relates to a stereo slide mount capable of adjusting the pitch for mounting the films, to a stereo slide viewer equipped with a function for adjusting the pitch of the stereo slide mount for mounting the films, and to a collimation pattern mask used for the stereo slide viewer.
2. Description of the Prior Art
In almost all stereo cameras, the distance between the optical axes of the right and left photographing lenses has been fixed, and the photographing ranges of the right and left photographing lenses are brought into agreement with each other at an infinite point. In the stereo cameras of the type in which the distance between the optical axes is fixed, the pitch between the same subjects on the right and left photographed pictures varies depending upon the distance to the subject. The pitch between the subjects at an infinite point is equal to the pitch between the right and left pictures, and the pitch between the subjects becomes wider than the pitch between the pictures as the distance to the subject decreases.
The images on the photographed pictures have been turned upside down. Therefore, the right and left films are turned by 180 degrees and are mounted on the stereo slide mount in a state of an erect image. Here, if the films are mounted with the pitch between the pictures of the right and left films being brought into agreement with the pitch between the right and left windows of the stereo slide mount, then, the pitch between the subjects in a close range becomes smaller than the pitch between the right and left windows.
When the stereo slide mount mounting the films in this state is viewed by using a stereo slide viewer, then, a stereo image of the subject in a close range appears in front of the stereo window (aerial image that appears as a single window as the right and left windows of the stereo slide mount are brought into agreement), offering unnatural perspective feeling and causing fatigue to the eyes.
In order that the image of the subject in the closest range appears to be at the same distance as, or slightly farther than, the stereo window, the pitch between the right and left films must be so adjusted that the pitch of the subjects in the closest range becomes larger than the pitch between the right and left windows of the stereo slide mount.
There have also been proposed a stereo camera in which the distance between the optical axes of the right and left photographing lenses is automatically adjusted so that the photographing ranges of the right and left photographing lenses are brought into agreement at a focal distance and a stereo camera which enables the distance between the optical axes of the right and left photographing lenses to be manually adjusted. Even in the stereo cameras of these types, however, the body at a distance closer than the focal distance in many cases appears in front of the stereo window unless the pitch between the right and left films is adjusted at the time of mounting the films.
However, the amount for adjusting the pitch of the films is so small that it is not easy to judge the correct positions for mounting the films by naked eyes.
Thus, there arouses a technical problem that must be solved in order to easily and correctly adjust the pitch of the films mounted on the stereo slide mount. The object of the present invention is to solve the above-mentioned problem.